The present invention relates generally to medical devices, systems and methods, and more particularly to small, low cost, portable infusion devices and methods that are useable to achieve precise, sophisticated, and programmable flow patterns for the delivery of therapeutic liquids such as insulin to a mammalian patient. Even more particularly, the present invention is directed to a dispenser for a fluid delivery device that utilizes a shape memory element.
Today, there are numerous diseases and other physical ailments that are treated by various medicines including pharmaceuticals, nutritional formulas, biologically derived or active agents, hormonal and gene based material and other substances in both solid or liquid form. In the delivery of these medicines, it is often desirable to bypass the digestive system of a mammalian patient to avoid degradation of the active ingredients caused by the catalytic enzymes in the digestive tract and liver. Delivery of a medicine other than by way of the intestines is known as parenteral delivery. Parenteral delivery of various drugs in liquid form is often desired to enhance the effect of the substance being delivered, insuring that the unaltered medicine reaches its intended site at a significant concentration. Also, undesired side effects associated with other routes of delivery, such as systemic toxicity, can potentially be avoided.
Often, a medicine may only be available in a liquid form, or the liquid version may have desirable characteristics that cannot be achieved with solid or pill form. Delivery of liquid medicines may best be accomplished by infusing directly into the cardiovascular system via veins or arteries, into the subcutaneous tissue or directly into organs, tumors, cavities, bones or other site specific locations within the body.
Parenteral delivery of liquid medicines into the body is often accomplished by administering bolus injections using a needle and reservoir, or continuously by gravity driven dispensers or transdermal patch technologies. Bolus injections often imperfectly match the clinical needs of the patient, and usually require larger individual doses than are desired at the specific time they are given. Continuous delivery of medicine through gravity feed systems compromise the patient""s mobility and lifestyle, and limit the therapy to simplistic flow rates and profiles. Transdermal patches have special requirements of the medicine being delivered, particularly as it relates to the molecular structure, and similar to gravity feed systems, the control of the drug administration is severely limited.
Ambulatory infusion pumps have been developed for delivering liquid medicaments to a patient. These infusion devices have the ability to offer sophisticated fluid delivery profiles accomplishing bolus requirements, continuous infusion and variable flow rate delivery. These infusion capabilities usually result in better efficacy of the drug and therapy and less toxicity to the patient""s system. An example of a use of an ambulatory infusion pump is for the delivery of insulin for the treatment of diabetes mellitus. These pumps can deliver insulin on a continuous basal basis as well as a bolus basis as is disclosed in U.S. Pat. No. 4,498,843 to Schneider et al.
The ambulatory pumps often work with a reservoir to contain the liquid medicine, such as a cartridge, a syringe or an IV bag, and use electromechanical pumping or metering technology to deliver the medication to the patient via tubing from the infusion device to a needle that is inserted transcutaneously, or through the skin of the patient. The devices allow control and programming via electromechanical buttons or switches located on the housing of the device, and accessed by the patient or clinician. The devices include visual feedback via text or graphic screens, such as liquid crystal displays known as LCD""s, and may include alert or warning lights and audio or vibration signals and alarms. The device can be worn in a harness or pocket or strapped to the body of the patient.
Currently available ambulatory infusion devices are expensive, difficult to program and prepare for infusion, and tend to be bulky, heavy and very fragile. Filling these devices can be difficult and require the patient to carry both the intended medication as well as filling accessories. The devices require specialized care, maintenance, and cleaning to assure proper functionality and safety for their intended long term use. Due to the high cost of existing devices, healthcare providers limit the patient populations approved to use the devices and therapies for which the devices can be used.
Clearly, therefore, there was a need for a programmable and adjustable infusion system that is precise and reliable and can offer clinicians and patients a small, low cost, light-weight, easy-to-use alternative for parenteral delivery of liquid medicines.
In response, the applicant of the present application provided a small, low cost, light-weight, easy-to-use device for delivering liquid medicines to a patient. The device, which is described in detail in co-pending U.S. application Ser. No. 09/943,992, filed on Aug. 31, 2001, includes an exit port, a dispenser for causing fluid from a reservoir to flow to the exit port, a local processor programmed to cause a flow of fluid to the exit port based on flow instructions from a separate, remote control device, and a wireless receiver connected to the local processor for receiving the flow instructions. To reduce the size, complexity and costs of the device, the device is provided with a housing that is free of user input components, such as a keypad, for providing flow instructions to the local processor.
What are still desired are new and improved components, such as dispensers and reservoirs, for a device for delivering fluid to a patient. Preferably, the components will be simple in design, and relatively compact, lightweight, easy to manufacture and inexpensive, such that the resulting fluid delivery device can be effective, yet inexpensive and disposable.
The present invention provides a device for delivering fluid, such as insulin for example, to a patient. The device includes an exit port assembly, a reservoir including a side wall extending towards an outlet connected to the exit port assembly, and a threaded lead screw received in the reservoir and extending towards the outlet of the reservoir. A plunger is secured to the lead screw and has an outer periphery linearly slideable along the side wall of the reservoir. The plunger and the lead screw are operatively arranged such that rotation of the lead screw in a first direction causes the plunger to slide along the side wall towards the outlet of the reservoir, which in turn causes fluid within the reservoir to be dispensed to the exit port assembly. The device also includes a dispenser having a shape memory element having a changeable length decreasing from an uncharged length to a charged length when at least one charge is applied to the shape memory element. The shape memory element has a first end secured to the lead screw, a portion of the elongated shape memory element wrapped around the lead screw, and a second end fixed with respect to the lead screw, such that the changeable length of the shape memory element decreasing from an uncharged length to a charged length causes rotation of the lead screw in the first direction. The use of a shape memory element helps provide a dispenser that is simple in design, and relatively compact, lightweight, and easy to manufacture.
The present invention provides another device for delivering fluid. The device includes an exit port assembly, a reservoir having a side wall extending towards an outlet connected to the exit port assembly, and a threaded lead screw received in the reservoir. A plunger is secured to the lead screw and has an outer periphery linearly slideable along the side wall of the reservoir. The plunger and the lead screw are operatively arranged such that rotation of the lead screw in a first direction causes the plunger to slide along the side wall towards the outlet of the reservoir. The device also includes a ratchet mechanism secured to the lead screw and including a wheel arranged such that rotation of the wheel in the first direction causes rotation of the lead screw in the first direction, while rotation of the wheel in a second direction causes no rotation of the lead screw. The device further includes a dispenser includes an elongated shape memory element having a changeable length decreasing from an uncharged length to a charged length when at least one charge is applied to the shape memory element. The shape memory element operatively connected to the wheel of the ratchet mechanism such that the changeable length of the shape memory element decreasing from an uncharged length to a charged length causes rotation of the wheel in one of the first direction and the second direction. An actuation element is secured to the wheel for moving the wheel in the other of the first direction and the second direction.
The present invention provides an additional device for delivering fluid. The device includes an exit port assembly, a reservoir including a side wall extending towards an outlet connected to the exit port assembly, and a threaded lead screw received in the reservoir. A plunger is secured to the lead screw and has an outer periphery linearly slideable along the side wall of the reservoir. The plunger and the lead screw are operatively arranged such that rotation of the lead screw in a first direction causes the plunger to slide along the side wall towards the outlet of the reservoir. A gear is secured to the lead screw and has radially extending teeth positioned to contact a first fixed member and prevent rotation of the gear and the lead screw in the second direction. The device also includes a dispenser having a slide positioned for linear movement adjacent the gear between a second fixed member and a third fixed member. The slide has a finger for engaging the teeth of the gear. The finger and the teeth are adapted such that linear movement of the slide past the gear towards the second fixed member causes rotation of the gear in the first direction, while linear movement of the slide past the gear towards the third fixed member causes no rotation of the gear. The dispenser further includes an elongated shape memory element having a changeable length decreasing from an uncharged length to a charged length when at least one charge is applied to the shape memory element. The shape memory element is connected between the slide and the third fixed member such that the changeable length of the shape memory element decreasing from an uncharged length to a charged length causes linear movement of the slide past the gear towards the third fixed member. An actuation element is connected between the slide and the second fixed member for causing linear movement of the slide past the gear towards the second fixed member when the charge applied to the shape memory element is removed.
The present invention provides a further device for delivering fluid. The device includes an exit port assembly, a reservoir including a side wall extending towards an outlet connected to the exit port assembly, and a threaded lead screw received in the reservoir. A plunger is secured to the lead screw and has an outer periphery linearly slideable along the side wall of the reservoir. The plunger and the lead screw are operatively arranged such that rotation of the lead screw in a first direction causes the plunger to slide along the side wall towards the outlet of the reservoir. A gear is secured to the lead screw and includes radially extending teeth positioned to contact a first fixed member and prevent rotation of the gear and the lead screw in the second direction. The device also includes a dispenser having a slide positioned for linear movement between the gear and a second fixed member, the slide including a finger for engaging the teeth of the gear. The finger and the teeth are adapted such that linear movement of the slide towards the gear causes rotation of the gear in the first direction while linear movement of the slide towards the second fixed member causes no rotation of the gear. The dispenser further includes an elongated shape memory element having a changeable length decreasing from an uncharged length to a charged length when at least one charge is applied to the shape memory element, the shape memory element connected between the slide and the second fixed member such that the changeable length of the shape memory element decreasing from an uncharged length to a charged length causes linear movement of the slide towards the second fixed member. An actuation element is connected between the slide and the second fixed member for causing linear movement of the slide towards the gear.
The present invention, therefore, provides a device for delivering fluid to a patient including new and improved components, such as dispensers and reservoirs. The components are simple in design, and relatively compact, lightweight, easy to manufacture and inexpensive, such that the resulting fluid delivery device is also relatively compact, lightweight, easy to manufacture and inexpensive such that the device can be inexpensive and disposable. In particular, the new and improved components of the present invention advantageously use shape memory elements to reduce complexity and costs.
The invention also provides an auxiliary component for use with the shape memory elements of the dispensers disclosed herein. An exemplary embodiment of the auxiliary component is provided in the form of an exit port assembly including a fixed member defining a channel having an outlet, and a transcutaneous patient access tool received for sliding movement in the channel towards the outlet. An actuation element is connected between the tool and a second fixed member for causing sliding movement of the tool towards the outlet of the channel, and a movable latch is positioned within the channel between the tool and the outlet. The exit port assembly also includes an elongated shape memory element connected to the latch such that the changeable length of the shape memory element decreasing from an uncharged length to a charged length causes movement of the latch out of the channel. The elongated shaped memory element can comprise one of the elongated shaped memory elements of the dispensers disclosed herein, such that a single elongated shaped memory element is used to operate two components.
The present invention provides still another device for delivering fluid. The device includes an exit port assembly, a fill port, and a reservoir including a side wall extending towards an outlet connected to the exit port assembly and an inlet connected to the fill port. A threaded lead screw is received in the reservoir and extends towards the outlet, and a plunger has an outer periphery slidably received on the side wall of the reservoir and an inner periphery slidably received on the lead screw. The plunger is non-rotatable with respect to the side wall and includes an insert having a threaded surface mateable with the threaded lead screw, and a spring biasing the threaded surface of the insert against the threaded lead screw such that rotating the lead screw in a first direction causes the plunger to slide along the side wall towards the outlet of the reservoir. The plunger also includes an elongated shape memory element having a first end secured to the insert and a second end extending radially outwardly from the insert and secured to the plunger, such that the changeable length of the shape memory element decreasing from an uncharged length to a charged length pulls the threaded surface of the insert away from the threaded lead screw. Applying a charge to the shape memory element, therefore, disengages the insert and allows the plunger to slide along the lead screw and away from the inlet of the reservoir during filling of the reservoir.
The present invention provides yet another device for delivering fluid. The device includes an exit port assembly, a fill port, a reservoir including a side wall extending towards an outlet connected to the exit port assembly and an inlet connected to the fill port, and a threaded lead screw received at least partly within the reservoir. A linearly fixed, annular gear is coaxially positioned on the threaded lead screw adjacent the reservoir and includes an insert having a threaded surface mateable with the threaded lead screw, a spring biasing the threaded surface of the insert against the threaded lead screw such that rotating the gear in a first direction causes the lead screw to move linearly towards the outlet of the reservoir, and an elongated shape memory element having a first end secured to the insert and a second end extending radially outwardly from the insert and secured to the gear. A changeable length of the shape memory element decreasing from an uncharged length to a charged length pulls the threaded surface of the insert away from the threaded lead screw such that the lead screw is movable linearly through the gear and away from the inlet of the reservoir. A plunger is secured to the lead screw and has an outer periphery linearly slideable along the side wall of the reservoir. During filling of the reservoir, the shape memory element can be charged to allow the plunger and lead screw to moved away from the fill port and the inlet of the reservoir.